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A common fold mediates vertebrate defense and bacterial attack

Carlos J Rosado1, Ashley M Buckle, Ruby H P Law

  • 1Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.

Science (New York, N.Y.)
|August 25, 2007
PubMed

Insights

The crystal structure of a bacterial membrane attack complex/perforin (MACPF) protein reveals similarities to cholesterol-dependent cytolysins. This suggests MACPF proteins may use a similar mechanism to form pores and disrupt cell membranes for defense.

Area of Science:

  • Structural biology
  • Immunology
  • Microbiology

Background:

  • Membrane attack complex/perforin (MACPF) domains are crucial in vertebrate immunity and development.
  • Vertebrate MACPF proteins like complement C9 and perforin form pores to lyse bacteria and kill infected cells.
  • The functional mechanism of MACPF proteins remains largely unknown.

Purpose of the Study:

  • To elucidate the structural basis and potential mechanism of MACPF protein function.
  • To investigate the relationship between bacterial and vertebrate MACPF proteins.

Main Methods:

  • Determined the crystal structure of the bacterial MACPF protein, Plu-MACPF from Photorhabdus luminescens, to 2.0 angstrom resolution.

Main Results:

  • The crystal structure of Plu-MACPF revealed significant structural similarity to pore-forming cholesterol-dependent cytolysins (CDCs) from Gram-positive bacteria.
  • This structural homology suggests a conserved pore-formation mechanism.

Conclusions:

  • Bacterial MACPF proteins, like Plu-MACPF, share structural folds with CDCs, indicating a potential conserved mechanism for membrane attack.
  • Vertebrates may utilize a CDC-like mechanism involving MACPF domains for immune defense against pathogens.

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